As IEC 61508, ISO 26262, and the like have been established as international standards on functional safety, needs for safety performance of automobiles are increasing.
In order to meet the needs for safety performance, a microprocessor installed in a vehicle transmission has been equipped with a function capable of constantly monitoring a safety state, such as higher performance of a fault detection function for a read only memory (ROM). On the other hand, due to technical improvements in microprocessors, a ROM storage capacity is rapidly increasing, and a ROM failure rate tends to be high.
There is disclosed a technology for shifting to a fail-safe state when a failure occurs, including a ROM failure, in a controller of a vehicle transmission.